Hydrosaurus celebensis ( Peters, 1872 )

Denzer, Wolfgang, Campbell, Patrick D., Manthey, Ulrich, Glässer-Trobisch, Andrea & Koch, André, 2020, Dragons in neglect: Taxonomic revision of the Sulawesi sailfin lizards of the genus Hydrosaurus Kaup, 1828 (Squamata, Agamidae), Zootaxa 4747 (2), pp. 275-301 : 290-292

Hydrosaurus celebensis ( Peters, 1872)

Chresonymy:

Lophura amboinensis ( Günther 1873: 168)

Lophura amboinensis (part) ( Boulenger 1885: 402; Meyer 1887: 6; Casto de Elera 1895: 417; de Rooij 1915: 128)

Lophura amboinensis var celebensis ( Weber 1890: 160, 167)

Hydrosaurus amboinensis (part) ( Wermuth 1967: 64)

Hydrosaurus cf. amboinensis ( Koch 2012: 149)

Hydrosaurus sp. [Sulawesi] ( Siler et al. 2014: 102)

Hydrosaurus celebensis ( Siler et al. 2014: 104)

Type: Holotype ZMB 7393 , adult male, collected by A. B. Meyer in 1870.

Type locality: “ Ufer des Flusses von Posso in der Bai von Tomini” (= banks of the Poso river in the Bay of Tomini), Central Sulawesi, Indonesia ( Figure 8 ) .

Description of holotype: See above.

Diagnosis: Large species, exceeding 1000 mm in total length, possibly 1200 mm (assuming TL/SVL = 2.4, a complete tail of holotype amounts to 864 mm); largest specimen examined, holotype SVL 360 mm, TL 580 mm (TL/SVL = 1.61), part of the tail missing; complete specimen, MZB Lac271, SVL 233 mm, TL 563 mm (TL/SVL = 2.42). Head, neck, gular region and shoulder completely black; a row of enlarged flat, sometimes conical scales on either side of the neck; nuchal and dorsal crests continuous; a group of dirty white enlarged flat scales on the anterior part of the dorsum; few (<10) additional enlarged scales approximately at midbody and before the hindlimbs. Dorsal colouration typically yellowish, sometimes dark orange, interspersed with black spots; ventrally beige, limbs black with a few yellow spots; scales under fourth and fifth toes broad with several keels from near the base of the toe; tail black, sail black or dark violet with black stripes.

Intraspecific Variation: The number of enlarged scales along the neck varies from three to five. Equally, the number of enlarged scales on the dorsum varies in the anterior group from two to seven. At midbody and near the base of the tail there are typically only one or two enlarged scales. One male from Pattunuang had the midbody group split into two groups of two scales giving the impression of a crossband. While the ventral scales in H. ce- lebensis are typically smaller than the dorsal scales, a photograph (courtesy of J. McGuire) of the specimen (tissue sample JAM 6859) from Desa Jelaja, Southwest Sulawesi, used in the phylogenetic analysis conducted by Siler et al. (2014) shows that the size of the ventral scales appear to be larger than or equal to the size of the dorsal scale size.

Sexual dimorphism: Adult males of H. celebensis have a considerably higher dorsal sail and a more developed nasal crest than in females. In general, the colouration and pattern is more contrasted in males while females appear to be duller in colour. Typically males of H. celebensis are black and yellow (or light orange) spotted whereas in females the spotted pattern is less pronounced consisting of an olive-brown, greyish ground colour with black spots in the Pattunuang population and rather greenish with light spots in the Palopo population. The colour of the head and anterior part of the neck is black in males while it is dark brown or grey with white speckles in females.

Comparisons: Hydrosaurus celebensis differs from H. amboinensis by the possession of the following characters: a group of strongly enlarged, flat scales on the anterior part of the dorsum. The colour on the dorsum is yellowish (vs. yellowish green in male H. amboinensis and green in females). Head, limbs and tail of male H. celebensis are completely or nearly completely black whereas both sexes in H. amboinensis have an entirely black marbled body. Additionally, the gular scales of H. amboinensis are round and irregular in size, while those of H. celebensis are minute and decreasing in size from the mental towards the onset of the gular pouch. H. celebensis differs from H. weberi in its general colour and pattern on the dorsum which is yellowish with black dots (vs. grey green in weberi ). H. celebensis differs from H. weberi and H. microlophus by less pronounced enlarged (i.e. armour-like) scales at the front of the forelimbs. In H. celebensis the nuchal and dorsal crests are continuous, while they are separated by considerably smaller scales on the neck in H. weberi .

Biology: H. celebensis was observed in a variety of habitats. In particular, the habitat of H. celebensis in the Pattunuang canyon differs from that in Bantimurung and near Palopo. The Pattunuang river is very stony and during the rainy season flows at a rapid pace. Its riverbank vegetation mainly consists of trees and only a few bushes. In Bantimurung specimens of H. celebensis were spotted in certain places where H. microlophus (see above) was not found. H. celebensis inhabited more inaccessible areas with dense vegetation on the banks and was often seen on branches above the water. Near Palopo H. celebensis inhabited an area near a slow flowing river without stones or rocks. Most of the individuals were found sitting in dense, low vegetation. Some of the subadults were spotted on thin branches above the water. In some places they were also spotted high up in trees where adults could be seen resting on branches. An adult female carrying eggs could also be observed in Pattanuang towards the end of March.

Distribution: H. celebensis is endemic to Sulawesi. It appears to inhabit the northern part of South Sulawesi, Central Sulawesi and South East Sulawesi ( Figure 8 ). The populations in Pattunuang and Bantimurung (South Sulawesi) are possibly a result of recent introductions according to a local source (A. Siady Hamzah, Universitas Hasanuddin, Makassar, UNHAS, pers. comm.) and information on the website of the Bantimurung-Bulusaraung National Park by Taufik Ismail (2013). See also the Discussion below.

Comparison between live specimens of H. microlophus and H. celebensis . Based on available photographs of live specimens from Sulawesi both species can be further distinguished by pholidosis, colouration and pattern. While some of the pictured specimens (mostly males) can be directly assigned to H. celebensis ( Peters, 1872) because they have a near identical appearance to that of the type specimen, others were quite difficult to identify and could only be assigned through inference to H. microlophus . In particular, juveniles within the presumed H. microlophus populations possess the same arrangements of groups of enlarged dorsal scales as the type specimen. All adults within the same populations also show these characteristic groups of enlarged lateral scales and we therefore consider these specimens as belonging to H. microlophus .

Specimens in various developmental stages of H. microlophus , were observed near Bantimurung, Bengo-Bengo / Camba and Rompegading on the southwestern peninsula of Sulawesi ( Figure 8 ). Figure 7 depicts a juvenile specimen from Rompegading displaying the characters described by Bleeker (1860). In particular the arrangement, size and shape of the enlarged dorsal scales fit well with the type specimen. Since the adult specimens of the southwestern peninsula differ vastly from both the holotype and live specimens of H. celebensis , hence we conclude that they represent H. microlophus . Adult males (and most females) from these populations have a much more pronounced scalation on the dorsum. The enlarged scales on the dorsum of the adults are strongly keeled and have a tetrahedral appearance (vs. near flat and only slightly keeled in H. celebensis ). In males these scales are black in colour and whitish to yellow in females. An additional feature seen in adult H. microlophus are the strongly enlarged scales on the anterior part of the forelimbs. This character very much resembles the description by Barbour (1911) for H. weberi who compared it to a piece of “armour”. The ground colour of adult H. microlophus males is generally dirty yellow, with the upper parts of the head, extremities and enlarged dorsal scales blackish. The gular region is yellowish. Adult females show a very different colouration ( Figure 3F ); the general dorsal ground colour is grey to dark grey or nearly black, while the enlarged scales are light. We did not observe or find a preserved adult male specimen with such a colouration nor did we find a female specimen with dark enlarged scales as described above. The colouration of some subadult females is very similar to that observed in juvenile specimens of both sexes (i.e., grey with cream coloured enlarged scales). The change in colour and development of the shape of the scales from one that is less to one that is more pronounced appears to be in line with ontogenetic development since only adult specimens show sexual dichromatism.

A second distinct phenotype ( Figures 3 C & D ) was photographed in the south of South Sulawesi (in the valley of the Pattunuang river and in Bantimurung) in the vicinity of a H. microlophus population and in the north of the Southwestern peninsula near Palopo ( Figure 8 ). Males of these populations agree completely with the holotype of H. celebensis (see Figure 4B ). They only have a few enlarged scales interspersed on the dorsum and their dorsal colouration is a pattern which is black and yellow spotted with white enlarged scales dorsolaterally. This particular colouration was observed during the dry season. During the wet season several males, but not all, displayed an even richer colouration, showing contrasts with the yellow coloured scales switching to a bright orange yellow colour. Head, gular region and extremities were completely black. Typically, females were slightly duller in colouration and less rich in contrast. Unfortunately, we were not able to find a juvenile within these populations that we could refer unambiguously to H. celebensis . In both Pattunuang and Palopo where populations of H. celebensis were found, almost all juveniles had more or less slightly marked crossbands of enlarged scales. In particular, we found that the juveniles of Pattunuang agreed with the general characteristics described for the type of H. microlophus . Both in Pattunuang and Palopo adult microlophus have not been observed but in Pattunuang it is probable that they are in contact with celebensis because the next localities of microlophus are only ca. 7 km (Bantimurung) resp. about 10 km (Bengo-Bengo) away.

Figures

FIGURE 3. Comparison of Hydrosaurus amboinensis with the two phenotypes observed on Sulawesi.A: Hydrosaurus amboinensis, male, Air besar (Passo), Ambon, B: Hydrosaurus amboinensis, female, Air besar (Passo), Ambon, C: Hydrosaurus celebensis, male, Pattunuang, Sulawesi, D: Hydrosaurus celebensis, female, Pattunuang, Sulawesi, E: Hydrosaurus microlophus, male, Rompegading, Sulawesi, F: Hydrosaurus microlophus, female, Ujung Lamuru, Sulawesi. Note the pronounced differences in colour pattern as well as number and arrangement of enlarged scales dorsolaterally. Photos by Andrea Glässer-Trobisch & Dietmar Trobisch.

FIGURE 4. A: The juvenile holotype (NHMUK 1863.12.4.35) of Istiurus (= Hydrosaurus) microlophus Bleeker, 1860 from Makassar, Southwest Sulawesi. Note the groups of enlarged scales on the dorsum. Photo by Patrick D. Campbell. B: The adult male holotype (ZMB 7393) of Lophura (= Hydrosaurus) celebensis Peters, 1872 from the Poso River, Central Sulawesi. Note the very few light enlarged scales on the dorsum. Photo by André Koch.

FIGURE 7. Juvenile specimen of H. microlophus from Rompegading displaying the characters described by Bleeker (1860). Photo by Andrea Glässer-Trobisch & Dietmar Trobisch.

FIGURE 8. Map of Sulawesi showing the distribution of H. microlophus (red) and H. celebensis (grey). Type localities are indicated by stars.. 0 Makassar; 1 Bantimurung; 2 Pattunuang; 3 Bengo-Bengo & Rompegading; 4 Camba; 5 Ujung Lamuru; 6 Belopa; 7 Palopo-Pompengan & Palopo-Siguntu; 8 Toraja; 9 Malele; 10 Poso River, Bay of Tomini; 11 Desa Jelaja; 12 Wasponda; 13 Desa Limbatu; 14 Morowali Nature Reserve; W1 Tempe („at the Minralang river near Tempe“ after Weber1890: 167); W2 Pampanua („at Pampanua on the river Tjinrana“ after Weber 1890: 167)